Detecting the battery capacity of UPS power supply requires a combination of theoretical calculations and actual testing. The following are specific methods and operational steps:
1、 Obtain basic parameters through the instruction manual or nameplate
View battery specifications
The battery capacity of most UPS power supplies is labeled as rated voltage (V) x rated capacity (Ah), measured in Wh (watt hours).
For example, if the voltage of the battery pack is 48V and the capacity is 10Ah, then the theoretical capacity is 48V × 10Ah=480Wh.
Note: Some UPS systems may use multiple batteries connected in series (e.g. 12V battery x 4 batteries=48V), and the total capacity should be calculated after confirming the capacity of each battery.
Confirm the rated power of UPS
Check the rated output power (VA or W) on the UPS nameplate, and estimate the theoretical endurance time based on the theoretical battery capacity: theoretical endurance time (hours) battery capacity (conversion efficiency) load power ()
Example: If the battery capacity is 480Wh and the load power is 200W, the theoretical endurance is about 1.92 hours.
2、 Actual discharge test (precise detection method)
preparation
Ensure that the UPS is fully charged and the load is at a stable power (to avoid fluctuations affecting test results).
Disconnect the mains power and let the UPS only be powered by the battery, while monitoring the load power with a power meter and recording the discharge time with a timer.
Operation steps
Start discharging
Disconnect the mains power input and observe whether the UPS switches to battery mode (some models require manual triggering for testing).
Immediately record the current time and ensure that the load is running normally.
Monitor voltage and time
Record the battery pack voltage (using a multimeter to measure the battery terminal voltage) and remaining time every 5-10 minutes.
When the UPS issues a low battery alarm or automatically shuts down, record the total discharge time.
Calculate actual capacity
Calculate the actual battery capacity based on the actual discharge time and load power:
Actual capacity (Wh)=load power (W) × discharge time (hours)
Comparison of theoretical capacity: If the actual capacity is lower than 80% of the theoretical value, the battery may age and need to be replaced.
precautions
1. Safety first: Before operation, be sure to cut off the power and avoid contact with battery terminals or UPS internal circuits to prevent short circuits or electric shock.
2. Regular maintenance: It is recommended to conduct a discharge test every 6-12 months. The lifespan of lead-acid batteries is usually 3-5 years, and aging batteries should be replaced in a timely manner.
3. Environmental impact: High temperature (>25 ℃) will accelerate battery aging, while low temperature will reduce actual capacity. Environmental temperature should be considered during testing.
By using the above methods, the actual capacity of UPS batteries can be accurately evaluated to ensure that the system can operate normally during power outages.
